SJN

Hi Guys.

I have installed my MVVS 35 in a cap 232 with a krumscheid canister KS 86V-4
It flys fine, and has good power, but I think my RPM`s might be on the low side.
It peaks at 6800rpm with a Metts 20/8 wooden prop.

Then I was thinking, that maybe my header is too long or short.

Is there a rule on what the distance should be from the exhaust port on the engine, to the muffler ?

pe reivers

Every canister has it's own specific length that goes with the prop in use.
I do not know the KS canister. Splice in a piece of tube to lenthen the header. If rpm drop, then you could try shortening the header until you have best performance.
You may want to give KS a call?

SJN

Thanks PE.

I anticipated an nswer like this, but sometimes you can get lucky, and someone has tried this combinatin before
Ill talk to krumscheid, to see what they have to say.

SJN

Fast answer from krumscheid

Hello,
you get the best results with a neutral-header-lenght from 180-260 mm.

If you have any questions, don´t hesitate to contact us.

Best regards

Klaus Krumscheid

pe reivers

It still is good to check different length within the range provided by KS. 6800 is slightly low.

SJN

In what area of rpm do you think it should be in ?

My motor has run about 3 liters of fuel.
Im rinnung it with 4% oil. an 95 octane.

Will using V-power 99 octane, and 2,5% oil increase the rpm ?


Also, at 75 to 100% throttle, my 20/8 prop makes alot of noise..... i guess the prop tips area at the speed of sound ?
Which size prop do you think I should try, to reduce this noise ?
My club is very noise sensitive.

pe reivers

Less oil will not increase rpm if you have the needles adjusted well, 99 octane V-power maybe a few rpm more, but not more than 25-50
at 6800 rpm, the prop will not be noisy. Is your tach OK? A 20"prop will get noisy above 7500 rpm. The engine works well with a 20x10 prop. That should keep the noise down.

SJN

Pe, maybe my tach is bad. My plane realy has good power, and the prop rips the air at high throttle.
Ill try borrow one of the other guys tach`s

Ill order a 20/10 carbon mejzelik prop.

microdon2

My Feedback: (47)

Pe - I have a Hangar 9 P51 150 (bought it used, here on RCU). It came with an MVVS 35 inside, with only a header pipe hanging outside the cowl. It's loud as hell - 96 decibels! I need a muffler, but this cowl is very tight with this engine inside. Can you recommend something? I've thought of a pipe, but, with these removable wings and all the wires inside there's really no room. Would love to do something like a JTec Pitts muffler. I see on the MVVS site a side muffler, but pretty sure that would not fit inside this cowl. Any suggestions? Thanks.

Mike

pe reivers

Other than the 3271 side muffler or tuned pipe, MVVS has no current solutions.
There used to be a sheetmetal side muffler called "compact muffler", item # 3098. E-bay may help here.